There two main groups of asbestos:
- Amphibole, which is characterized by straight, needle-like fibers. The commercial forms of amphibole include crocidolite or blue asbestos, and amosite or brown asbestos. Both of these forms are mined in South Africa and Australia.
- Serpentine, which is characterized by curly fibers. Chrysotile or white asbestos is the only form that is used commercially. It is mined in Canada, but it accounts for over 90 percent of asbestos used in the United States.
Exposure in the U.S. is estimated to be approximately between 2-6 million people. In the late 1970s, high exposure levels stopped because of legislation initiated as a result of the discovery of asbestos’ toxicity.
Asbestos exposure has been mainly industrial or occupational. Workers with the most significant exposure are those who mined or processed asbestos, those that used asbestos-related products in the shipbuilding and construction industries, and those that created asbestos-containing products in the textile and insulation manufacturing industries.
The latency period between exposure and the development of asbestos-related disease is at least 20 years, which is why these diseases are still a health issue.
The Asbestos-Related Disease Spectrum Includes Both Benign and Malignant Conditions
The most commonly thought of diseases associated with asbestos exposure are mesothelioma and lung cancer. In addition, other cancers including kidney, colorectal, laryngeal and esophageal have been linked with exposure in some studies.
However, there are some other conditions that can develop:
Benign Pleural Effusion
The pleural effusion is fluid, which often has traces of blood, with no characteristics of any kind when analyzed. Benign pleural effusions develop approximately 10 years after exposure to asbestos and can be the precursor of asbestos-related diffuse pleural thickening. Patients with this condition may not present with any symptoms.
If they do exhibit symptoms, these would include shortness of breath, pain and fever. The symptoms can spontaneously disappear and then return. The risk of developing benign pleural effusion is dose dependent, meaning the individual needs to have had a high level of exposure to asbestos. However, there have been cases in which patients developed the condition with only limited exposure.
Pleural Plaques
This is the most common condition resulting from asbestos exposure. It is characterized by the formation of thick white or yellow areas on the parietal pleura, the part of the membrane that attaches to the chest wall. They frequently form on both sides of the posterior region of the chest wall between the fifth and eighth ribs, over the part of the pleura that covers the space between the lungs and on the dome of the diaphragm.
Pleural plaques usually develop 20 to 30 years after asbestos exposure. The risk of developing them increases with the level of exposure. They can also develop after limited exposure.
Diffuse Pleural Thickening
This condition creates extensive scar tissue formation on the visceral pleura, the part of the membrane that covers the lung. It also causes a fusion between the visceral and parietal pleurae, wiping out the pleural space between the two. Diffuse pleural thickening typically follows the development of benign pleural effusion.
The most common symptoms are shortness of breath upon exertion and chest pain. Diffuse pleural thickening is progressive and may result in substantial decrease in lung function.
Rounded Atelectasis
This condition is sometimes called folded lung, or Blesovsky syndrome, or shrinking pleuritis with atelectasis. It results from scar tissue forming on the visceral pleura which traps and rolls into the underlying lung. It appears as a rounded mass between 2 and 5 centimeters in diameter with pieces of collapsed lung tissue protruding through it.
Patients with this condition do not usually exhibit symptoms, but some may experience shortness of breath and a persistent cough. Generally, rounded atelectasis progresses slowly, and no specific treatment is required.
Asbestosis
This condition causes inflammation in the branches of the alveoli, which are tiny air sac inside the lungs. It is characterized by an influx of large white blood cells within the alveoli that ingest inhaled particles. The most common symptoms exhibited with this condition are shortness of breath upon exertion, which worsens as the disease advances, a persistent cough, and chest pain. Asbestosis can lead to heart and lung failure.